The present arrangement relates to seal arrangements and more particularly to seal arrangements utilised with respect to rotating shafts and the like and formed from leaf elements or bristles.
Provision of appropriate seal arrangements in machinery such as gas turbine engines is important in order to separate operational stages within that machinery and for other reasons. The seal arrangements must be efficient but also have sufficient durability for acceptable operational periods before replacement and/or maintenance. It is known to provide brush seals which comprise bristles which extend towards a rotating shaft in operation in order to provide a seal between one side of the shaft and the other. The bristles through their tips rest or more normally ride slightly above the surface of the rotating shaft on a marginal leakage flow in order to create a seal. More recently, leaf seals have been developed which comprise leaf elements typically in the form of flexible metal tabs which extend towards the rotating shaft such that bottom tip edges of the tabs are again adjacent to the surface of the rotating shaft in order to create a seal. It will be understood that it is the tips of the bristles or edges of the leaf elements which determine the sealing effect but generally a degree of flexibility must be provided to take account of shaft misalignment and deviations in rotation due to imbalance such as a result of torque loading or otherwise. In such circumstances, as much control as possible of the bristles or leaf elements in order to maintain the appropriate presentation of these bristles or elements to the shaft is desirable.